The technology described herein relates to a method of and an apparatus for generating an output surface (such as a window to be displayed) from one or more input surfaces (such as input windows) in data processing systems.
Many known electronic devices and systems use windows for displaying information, such as a graphical user interface, game, demo, etc., to a user on a display screen (and for allowing a user to interact with an application or applications being executed). A common way of displaying such windows is to use a so-called compositing window system, in which the individual windows are first stored in (rendered to) respective window buffers, and then the individual window buffers (i.e. their content) are combined appropriately into a unified frame buffer for the display in question in order to display the windows to the user. In this arrangement, the individual input windows will accordingly form one or more input surfaces that are then combined by the compositing window system into an output surface (the unified frame buffer) for display.
While such compositing window systems are generally believed to be preferable to systems where each window is rendered to the frame buffer directly, they can still require significant resources in terms of memory bandwidth, processing and power consumption.
Studies have shown that with mobile device use, most of the time (around 75%) is spent on User Interface (UI) generation and composition, whereas around 15% is spent on basic 3D apps and 3D composition and the remaining 10% is spent on less basic 3D apps and games and their composition.
Composition uses a significant amount of memory bandwidth and power. For example, a study has shown that 2,179 MB/s is consumed for an Android type application for HD resolutions in many systems.
The Applicants believe that there remains scope for improvements to arrangements, such as compositing window systems, in which an output surface is generated from one or more input surfaces.
Like reference numerals are used for like features throughout the drawings, where appropriate.